This invention relates to a novel p-fluoroaniline derivative or a salt thereof and a process for determining the amount of an oxidative substance or a peroxidase-like substance by using the p-fluoroaniline derivative or salt thereof as a color producing component.
Measurement of living body components, for example, body fluid components such as blood and urine is indispensable for diagnoses of diseases, elucidation of pathosis, and judgement of progress towards recovery because the change of amounts of the living body components is closely related to diseases. There have been developed methods for measurement of great many body fluid components such as cholesterol, triglycerides, glucose, uric acid, phospholipids, bile acid, monoamine oxidase, etc. in blood. It is generally known that these methods are useful for diagnoses of diseases.
As methods for measurement of serum components, so-called "enzymatic methods" have been generalized. In the enzymatic methods, when an objective component is other than enzymes, there is used an enzyme which acts specifically on the objective component. When an objective component is an enzyme, there is used a compound which is a substrate for the enzyme. In each of these cases, enzymatic reaction is carried out and the reaction product is measured, whereby the amount of objective component is determined. Of the enzymatic methods, there are being increased, with development of oxidizable color producing reagents, methods which comprise acting a hydrogen peroxide producing enzyme, for example, an oxidase on an objective component to produce hydrogen peroxide in an amount corresponding to the amount of the objective component, introducing the hydrogen peroxide into a color producing system using peroxidase and an oxidizable color producing reagent as color producing component, carrying out calorimetric determination on the basis of the coloration thus caused, and thereby determining the amount of the objective component. An example of such methods is a method which comprises introducing hydrogen peroxide produced by a combination of cholesterol and cholesterol oxidase; a triglyceride, lipoprotein lipase and glycerol oxidase; uric acid and uricase; or the like into a color producing system using peroxidase (POD) and an oxidizable color producing reagent, measuring absorbance due to the coloration thus caused, and thereby determining the amount of an objective component. Typical examples of the oxidizable color producing reagent used as color producing component in this method are a combination of 4-aminoantipyrine or a derivative thereof and a phenolic compound or an N,N-disubstituted aniline compound; a combination of 3-methylbenzothiazolinone hydrazone (MBTH) and an aniline compound; 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS); triphenylmethane series leuco dyes; benzidine derivatives; o-tolidine derivatives; triarylimidazole derivatives; o-phenylenediamine, etc.
These color producing reagents, however, involve various problems. For example, a dye produced from them is faded by the influence of serum components, the dye has an absorption maximum in a short wavelength region and hence tends to be affected by colored components in a sample, such as hemoglobin, bilirubin, etc. in serum and urine, resulting in low reliability of measured values, and the dye gives a low measuring sensitivity because of its small molecular extinction coefficient, so that the color producing reagents can be utilized only for measurement of a few analytes to be measured. Thus, the color producing reagents have been not always satisfactory.
For solving such problems, there has been developed a p-fluoroaniline derivative obtained by introducing a fluoro group into an aniline derivative (Japanese Patent Unexamined Publication No. 60-243050). Moreover, a dye produced from such an existing p-fluoroaniline derivative is somewhat improved in the fading caused by the influence of serum components but are not yet free from the problem that the dye has an absorption maximum in a relatively short wavelength region and hence tends to be affected by colored components in a sample, such as hemoglobin, bilirubin, etc. in serum and urine, resulting in low reliability of measured values. Therefore, there is a desire to seek further improvement in the color producing reagents.